1. Field of the Invention
The present invention relates to a slide bearing having high accuracy, excellent sliding characteristics and strength characteristics.
2. Description of the Related Art
Slide bearings made of Cu-based, Cu—Sn-based and Fe—Cu-based sintered metal materials have been known as slide bearings having high rotational accuracy. When the slide bearing is used after a bearing member made of a porous sintered metal material is impregnated with a lubricant (sintered oil-containing bearing), the lubricant can be continuously supplied to a sliding portion between the bearing and a shaft member. The bearing member made of a sintered metal material can improve in processing accuracy and is suitable for use in a portion requiring rotational accuracy.
Resin slide bearings manufactured by mixing a solid lubricant such as PTFE, graphite or molybdenum disulfide, lubricating oil or wax with a resin material are also known as slide bearings.
Further, slide bearings having a resin layer on a predetermined surface of a matrix made of a sintered metal material are also known (see JP 2002-364647 A (hereinafter referred to as “Patent Document 1”), for example).
When a shaft member to be supported is made of a soft metal material such as aluminum alloy material, a slide bearing made of a sintered metal may damage the sliding surface of the shaft member.
In the case of using a resin slide bearing, the above problem does not occur. However, since resin materials typically have a larger linear expansion coefficient and higher water absorptivity than metal materials, when the use temperature range of the resin slide bearing is wide, a backlash between the bearing and the shaft member due to the shrinkage of the resin material during use at a low temperature and the outer diameter of the bearing may increase due to the expansion of the resin material during use at a high temperature. When the outer diameter of the bearing is restricted by a housing or the like, the inner diameter of the bearing shrinks, thereby causing the so-called “clamping” of the bearing to the shaft member in some cases. Since the slide space between the shaft member and the slide bearing is changed by volume expansion caused by water absorption, it is difficult to use the slide bearing in fields that require rotational accuracy such as a field of office equipment.
A slide bearing having a resin layer on a predetermined surface of a matrix made of a sintered metal material makes it possible to eliminate the above inconvenience. When using in the devices in which the outer peripheral surface of a matrix comes into contact with a mating member to roll or slide, such as cam followers, the outer peripheral surface of the matrix tends to be damaged due to the insufficient strength of the matrix.